Bosch Rexroth Ag

Brueninghaus Hydromatik Gmbh

Graham Perry

Sinclair Upton Cunningham

Heinz-Gerhard Essig

Chris Shrive

A hydrostatic power train includes a hydraulic pump, which is connected, via a first main pipe and a second main pipe, to a first hydromotor unit driving a front axle and to a second hydromotor unit driving a rear axle. The first and second hydromotor units can be adjusted in terms of their displacement via a first and second variation device. A direction of travel is defined as forward movement (F) or reverse movement (R) by a position of an operating lever. The first and the second variation devices are controlled by a control valve which takes up a first control position upon a forward movement (F) determined by the position of the operating ever and which takes up a second control position upon reverse movement (R) determined by the position of the operating lever and which takes up a second control position upon reverse movement (R) determined by the operating lever. In the first control position, the first variation device is controlled such that the first motor unit is adjusted for a smaller displacement and, in the second control position; the second variation device is controlled such that the second motor unit is adjusted for a smaller displacement.

Control for a hydrostatic power train

A drive mechanism is disclosed which includes a hydraulic pump whereby at least two hydraulic motors may be supplied with pressure medium. The drive mechanism in accordance with the invention has on the meter-in side or on the meter-out side of each hydraulic motor a variable hydraulic resistor that is biased into a basic position of minimum open cross-section and may be subjected to a control pressure in a direction of increased open cross-section. This control pressure is dependent on the pressure on the meter-in side or on the meter-out side of the hydraulic motor.

Drive mechanism

The invention relates to a hydrostatic traveling mechanism ( ) which comprises a hydraulic pump ( ), a first hydraulic engine ( ) that is linked with the hydraulic pump ( ) via a hydraulic work circuit ( ) and that drives a first drive train ( ). The traveling mechanism further comprises a second hydraulic engine ( ) that is linked with the hydraulic pump ( ) via a hydraulic work circuit ( ) and that drives a second drive train ( ). The inventive traveling mechanism is also provided with a third hydraulic engine ( ) that is coupled with the first drive train ( ) and a fourth hydraulic engine ( ) that is coupled with the second drive train ( ). The third hydraulic engine ( ) and the fourth hydraulic engine ( ) are linked with each other via a hydraulic secondary circuit ( ) that is independent of the work circuit ( ).

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Edinburgh, United Kingdom

Graham Perry